The equations $2 x^2+a x-2=0$ and $x^2+x+2 a=0$ have exactly one common root. If $a \neq 0$, then one of the roots of the equation $a x^2-4 x-2 a=0$ is

If $\alpha, \beta$ and $\gamma$ are the roots of the equation $2 x^3-3 x^2+5 x-7=0$, then $\sum \alpha^2 \beta^2=$

The sum of two roots of the equation $x^4-x^3-16 x^2+4 x+48=0$ is zero. If $\alpha, \beta, \gamma$ and $\delta$ are the roots of this equation, then $\alpha^4+\beta^4+\gamma^4+\delta^4=$

If $\alpha, \beta$ are the roots of $x^2+a x+2=0$ and $1 / \alpha, 1 / \beta$ are the roots of $x^2-b x+c=0$, then

$$ \left(\alpha+\frac{1}{\beta}\right)\left(\beta+\frac{1}{\alpha}\right)\left(\alpha-\frac{1}{\alpha}\right)\left(\beta-\frac{1}{\beta}\right)= $$